Rolling mill



March 8,1927.

L. LEE

ROLLING MILL Filed Aug. 1920 March 8, 1927. L. LEE

ROLLING MILL 3 Sheets-Sheet 2 Filed Aug. 1920 I I gwuentoz M @Hozneg L.LEE

ROLLING MILL March .8 1927.

Filed Aug. 1920 3 Sheets-Sheet s Patented Mar. 8, 1927.

UNITED STATES LEIF LEE, F YOUNGSTOWN, OHIO.

. ROLLING MILL.

Application filed August 30, 1920. Serial No. 406,946.

This invention has relation to certain new and useful improvements inrolling mills, and more particularly to mills for use in rolling steelsheets.

In mills of this character, several stands of rolls are usuallyconnected in line, the first or roughing passes being performed on oneset of rolls and the finishing passes on another set of rolls. Thebottom roll of each 1 set is positively driven, all the bottom rollsbeing connected b couplings to form a continuous shaft. T e top rollsare usually not positively driven but are caused to rotate by thefriction of the entering pieces, Consequently, the thickness of thepiece is limited to that which willenter the rolls, In order to use awider range in the thickness of the pieces and to insure that the pieceswill enter the rolls quickly and surely,

several methods have heretofore been used for driving the top roll ofthe roughing rolls.

The present invention is designed to provide improved means of novel andefiicient character for driving the top roll of a sheetmill roughingstand, and which possess several important advantages, hereinafterpointed out, over the means heretofore employed for such purpose.

The nature of the invention and its mode of operation will best beunderstood by reference to the accompanying drawings, in which:

Figure 1 is an end view of a roughing stand having my invention appliedthereto;

Figure 2 is a vertical section of one form of a reducing and slip gearwhich may be employed; and

Figure 3 is atop plan view of the portion of a sheet mill embodying myinvention.

Figure 4 isv a partial sectional view approximately on line IVIV ofFigure 2, the

ousing being omitted.

Figure 5 is an electrical diagram illustrating the connections for theinduction motor.

In these drawings, 2 designates the bottom, and 3 the top roll of asheet mill roughing stand, said rolls being mounted in any usual orsuitable manner in the housings 4. 5 is the top roll of an adjacentfinishing roll stand. 6 desi nates an electric motor mounted at the enof the rougher. This motor drives a worm 7 which meshes with a wormwheel 8, loosely mounted on a shaft 9, said v2 and 4 herein. That devicecomprises a hub 14 loosely mounted on the shaft 9 and to which the wormgear 8 is bolted. A member havin an annular flange 15 is alsoi bolted tot e hub 14. The flange 15 is provided with a lurality of equally spacedgrooves 16, as s own in Figure 4. A memer 10 is keyed to the shaft 9 andhas two diametrically opposite arms. Levers 17 are pivotally mounted onthe arms of the member 10, as shown in Fi re 4. In one end of each ofthe levers 1 is placed a roller 18 which engages the grooves 16 in theflange 15. To the other end of each of the levers 17 is pivotallyconnected a rod 19. The two levers and their connecting means areidentical, and therefore a description of one will be sufiicient' forboth. A' spring 20 surrounds the rod 19, and one end of the spring 20engages a housing 21 on the member 10. The other end of the spring 20engages a collar 22 which is held in place on the rod 19 by the nuts 23.The tension of the spring 20 may be changed to chan e the pressure ofthe rollers 18 against t e flange 15. The flange 15' is positivel drivenby the worm 7, and drives the sha 9 through the rollers 18 and member10. If the resistance to the shaft 9 is suflicient to cause the rollersto ride out of the grooves 16, the flange 15 may rotate relative to theshaft 9. If that resistance is not great enough to cause this relativemovement, the shaft 9 is driven at the same speed as the flange 15. 11designates a suitable housin for the reducing and slip gear. The sha t 9is connectedto the top roll 3 by means of the short shaft 12 and theuniversal joints 13. The joints 13 are rovided in order to take care ofvarying distances between the centers of. the rolls 2 and 3. Anarrangement for automatically controlling the motor is shown in Figure5. The wires 24 lead from the rotor of the motor 6 to resistances 25 and26. These wires in passing to the resistances include solenoid coils 27arranged on a core 28. An armature 29 is arran ed above the core 28 andis adapted to be pul ed down by the coils 27 upon the passing of apredetermined current through the coils 27. The armature 29 is normallyheld in the position shown by a spring 30. A switch member 31 is pivotedat 32, and a link 33 connects the switch member 31 with the armature 29so that when the parts are in the position shown a circuit is closedthrough the wires 34. This circuit 34 includes the solenoids 35, whichact upon switch members 36 to hold circuits closed through the contacts37 and 38. When the contacts 37 and 38 are closed, the resistancesections 26 are short-circuited. When the coils 35 are de-energized, theswitch members 36 rest against the stops 39. The circuit of the coils 35is controlled by the switch member 31, which in turn is controlled bythe current in the rotor windings of the motor. The

operation of the arrangement shown is as follows:

The top roll 3 is so geared as to run at a speed slightly below that ofthe bottom roll 2. Whenthe steel starts between the rolls, it frequentlysticks during the biting period. This causes the to roll 3 to slow down,greatly increasing t e load on the motor 6. The load on the motorincreases from that required to overcome the friction of the top roll tothat required to roll the steel through the 'biting period includinfriction. After the steel is between the re ls, the top roll is drivenby friction through the steel from he lower roll at a higher speed thanthe normal speed of the motor 6, and the motor 6 is therefore relievedof load.

I prefer to employ for the motor 6 an alternating current motor of thewound rotor type with a gear reduction such as to run the top roll 3 ata slightly lower speed than the bottom roll. As above stated, after thesteel has entered the rolls, the top roll will speed up above thesynchronous speed of the motor. This will relieve the motor of load, andwill cause the generation of a small amount of pgwer in the motor; butthis power will not sufficient to substantially load the driving meansfor the lower roll.

The slip gear is so adjusted as to operate upon the occurrence of apredetermined overload, and acts independently of the electrical controlmeans for the motor, and its tendency is to definitely relieve the motorupon the occurrence of the predetermined overload in either direction.

When the load on the motor 6 increases to a predetermined amount whichis below the load, causing the slip gear to operate, the solenoid 27.will draw the armature 29 downwardly and cut the resistances 26 intothe armature circuit of the motor. This will decrease the speed of themotor and protect its windings against damage, but the motor willcontinue to operate at its lower speed and cause the steel to continueto move between the rolls. As soon as the steel passes the bitingperiod, the top roll will be speeded up, thus relieving the load on themotor, whereupon the armature 29 will be raised and the resistances 26cut out of the motor armature circuit. From the foregoing, it istherefore evident that means are provided for positively operating thetop roll throughout the biting period, as well as means for protectingthe motor against damage by heavy current flow. The slip gear is alsoprovided for protecting the motor when the load exceeds a predeterminedmaximum.

The construction disclosed herein, besides being desirable by reason ofcertain of the mechanical features employed, is of mate rial advantageby reason of the fact that it keeps the two adjacent roll stands closeenough so that the distance between the rolls of the respective standspermits work to be transferred from one stand to the other in a singlethrow by a single operator. This-is highly desirable, as union rules inforce at the present time require two men where the distance isincreased beyond a certain limit. In such cases the mill is referred toas a double throw mill.

My invention provides an extremely simple and effective to roll drive ina mill of the character descri ed, since it gives the necessary rangefor thickness, and insures the proper and quick entry of the work piece,while relieving the auxiliary motor from actual work in rolling.

I do not limit myself to the particular embodiment of my invention whichI have herein shown and described, as many changes may be made thereinwithin the s irit and 'scope of the appended claims.

hus, any suitable form of auxiliary motor may be used; the type ofreducing gearing may be changed, and any suitable adjustable means forpermitting slip between the motor and the top roll at any torque abovethe safe motor torque may be employed.

. I claim:

1. In a rolling mill, the combination with a pair of rolls, of anelectric motor for driving one of said rolls independently of the drivefor the other of said rolls, and gearing connecting said motor with theshaft of the roll driven thereby, said motor and gearin being arrangedto normally drive said rol at a lower speed than the other roll, saidgearing including. slip means whereby, when a workpiece enters the rollsand thereby causes the speeding up of said motordriven roll, said motorwill be normally driven by said roll above the normal speed of saidmotor, said slip means being constructed to operate upon the occurrenceof a predetermined overload on said motor, substantially as described.

2. In a rolling mill,.the combination with a pair of rolls, of anelectric motor for driving one of said rolls independently of the drivefor the other of said rolls, and gearing connecting said motor with theshaft of the roll driven thereby, said motor and gearing being arrangedto normally drive said roll at a lower speed than the other roll, saidgearin including slip means whereby, when a wor piece enters therollsand thereby causes the speeding up of said motordriven roll, saidmotor will be normally driven by said roll'above the normal speed ofsaid motor, said slipmeans being constructed to operate upon theoccurrence of a predetermined overload on said motor and beingadjustable to operate at different overloads.

3. In a rolling mill, the combination with a pair of rolls, of meanspartly offset laterally withrespect to the rolls for driving one of saidrolls independently of .the drive for the other of said rolls, saidmeans'comprising an electric motor and a slip gear or clutch between themotor and roll shaft designed to slip in the direction of drive'upon theoccurrence of a predetermined overload on the motor, substantially asdescribed.

4. In a rolling mill, the combination with a'pair of rolls, of means fordriving one of said rolls independently of the drive for the other ofsaid rolls, said means comprising an electric motor ofi'set laterallywith respect to the rolls and a slip gear or clutch between the motorand roll shaft designed to slip in the direction of drive upon theoccurrence of a predetermined overload on the motor and being adjustableto operate at different overloads, substantially as described.

The combination with a two-high sheet rolling mill stand having a drivefor its bottom roll, of a separate alternating cur-- rent motor drivefor the top roll, said drive having means whereby an entering workpiecewill drive the top roll at a higher speed than the synchronous speed ofthe motor and thereby relieve said motor of rolling load, substantiallyas described. I 6. The combination with a two-high shee rolling millstand having a drive for its bottom roll, of a separate motor drive forthe top roll, said drive comprising an alternating current motor, andmeans for affect-- ing the circuit of said motor to cause its 7 speed tobe reduced when a workpiece enters ranged to vary the resistance in therotor circuit upon increase in current pulled by the motor when theworkpiece enters the of rolling load, said motor having its arma-- tureshaft at substantially right angles to the axes of the rolls,substantially as described.

9. The combination with a two-high sheet rolling mill stand having adrive for its bottom roll, of a separate motor coupled to the top rollto continuously drive the same until the workpiece has entered therolls, together with means for causing the said motor to automaticallyslow down when a work piece enters the rolls, the slowing down of themotor being dependent upon the difficulty encountered by the workpiecein entering between the rolls, substantially as described. I

10. The combination with a roughing mill, of a finishing mill, saidmills having their rolls in end to end relationship, and meansintermediate the mills but ofiset laterally relatively thereto to drivethe top roll of the roughing mill while maintaining a single throwdistance between the mills, substantially as described.

11. The combination with a roughing mill, of a finishing mill, saidmills having their rolls in end to end relationship, and an electricmotor intermediate the mills but ofiset laterally relatively thereto todrive the top rolls of the roughing mills, while maintaining a singlethrow distance between the mills, substantially as described.

12. The combination with a roughing mill, of a finishing mill, saidmills having their rolls in end to end relationship, and meansintermediate the mills but offset laterally relatively thereto to drivethe top roll of the roughing mill while maintaining a single throwdistance between the mills, said means having a slip gear connectionwith the roll it drives, substantially as described.

13. The combination with a roughing mill, of a finishing mill, saidmills having their rolls in end to end relationship and having a singlethrow distance between the respec tive passes of the mills, a gearreduction intermediate the mills and operatively connected to the toproll of one of the mills, and means oflset laterally relatively to thegear reduction and mills for driving the gearreduction, substantially asdescribed.

14. The combination with a roughing mill, of a finishing mill, saidmills having their rolls in end to end relationship and having a singlethrow distance between the rcspective passes of the mills, a gearreduction intermediate the mills and operatively connected to the toproll of one of the mills, and means offset laterally relatively to the 5gear reduction and mills for driving the gear reduction, said meanscomprising an electric motor operative for' driving the top roll at alower speed than that at which the bottom roll is driven, substantiallyas described.

In testimony whereof; I have hereunto set my hand.

I \LEIF LEE.

